standard bakelite high pressure laminate

Click here to load reader

Post on 14-Jan-2016

34 views

Category:

Documents

0 download

Embed Size (px)

DESCRIPTION

RPC Development in Beijing and Potential for NO  A Tianchi Zhao University of Washington May 16, 2005. Standard Bakelite High Pressure Laminate. Produced in Italy Coordinated by INFN. Laminated by hot steel plates. SURFACE Melaminic phenolic resin with fine paper. BULK - PowerPoint PPT Presentation

TRANSCRIPT

  • RPC Development in Beijing and Potential for NOA

    Tianchi ZhaoUniversity of Washington

    May 16, 2005

  • Standard Bakelite High Pressure LaminateBULKPhenolic/melamine resin with regular compressed paperSURFACEMelaminic phenolic resinwith fine paperM. Abbrescia et al., Test on the Performance of Resistive Plate Chambers inView of Their Use at the LHC, International Conference on High EnergyPhysics of the European Physical Society, Jerusalem, Israel, August, 1997. Produced in Italy Coordinated by INFN Laminated by hot steel plates

  • Linseed oil : Haptane = 40 % : 60 % Oil coating at T = 30 ~ 32o Drying the coated oil with air for 48 hours Oiling Procedure for CMS End-cap RPCs200 l tank

  • Inventions Made at IHEP, BeijingSurfaceThin melamine film Much better surface quality than surfaces formed by fine paper and resin pressed by steel plates.

    A very simple technical improvement with a dramatic effect on the RPC performance (A) Pre-fabricated melamine film hot pressed on surface

  • (B): A special process of modifying the phenolic polymer to obtain the desired bulk resistivityBULKModified phenolic High resistivity: Low dark current, low noise -> low rate capability Low resistivity: High dark current, high nois -> high rate capability

  • (C) Graphite PaitingH.V. ElectrodesSpecial Graphite Paint for the melamine surface A special graphite paint compatible to melamine film was developed together with Chinese industry. Graphite layers is spray painted

  • RPC Prototypes R&D started four years ago Prototypes mostly a single gap, 0.6 m2 Various plate resistivity: 1011 to 4x1012 cm Streamer mode intended for low rate Performance improves as they learn

  • Prototype Performance Electrode resistivity: ~1012 cm Ar/Freon134/Isobutane 32:60:8 (Belle gas) Discrimination threshold: 100 mVBest results are from a recent neutron radiation test Long plateau: ~ 2000 V High efficiency 96-98% for a single 2 mm gap

  • Cosmic Ray Counting Rate Noise rate: 0.04 Hz/cm2 at 7.5 kV At the cosmic ray rate level (cosmic: ~0.03 Hz/cm2) Comparable performance as best oiled bakelite or glass RPCs

  • Dark Current ~0.5 A @7.5 kV No break down up to 9000 V

  • Status of BESIII RPCs Prototypes show the performance is as good as chambers made from oiled bakelite or glass A factory was setup in the south suburb of Beijing Pre-production started early 2004 Just has an internal production readiness review Making 2000 m2 RPCs in 2 years

  • Technical Details of BESIII RPC Standard double gap structure Single layer of pick up strips Bulk Resistivity: 2x1011 to 2x1012 cm

  • Technical Details Gap StructureSpacer Arrangement

  • Compare to Low Cost Glass RPCs Developed by MonolithEnd caps by injection moldingNorylEnvelope Thermoplastic solderingfor gas sealingSpacers by injection molding(2 mm)Float GlassResistive film Bakelite does not break Lower resistivity, bigger signal, slightly higher efficiency Bakelite RPC does not need a plastic envelop

  • Potential for NOA The factory in Beijing can make PRCs with maximum size 4x8 (5x10 in Europe)

    - Limited by their lamination press - Should be large enough for NOA

    They will be very happy to make a few for NOA

  • PlanFirst Step: Make several RPCs in Beijing and bring them back to U.S. for testing Single gap Double gap with three bakelite platesSecond Step:

    Make several 4x8 chambers with the gap configuration we like

    With readout electrodes and ground plane on particle board

    The treatment of the electrodes is done by filling the entire gas volume of a fully assembled RPC with linseed oil that is then slowly taken away. A subsequent process of polymerization of the oil is done by fluxing the emptied gas volume with dry air. The resulting effect is the deposition of a thin layer of oil on both bakelites surfaces facing the gas volume. under High Radiation EnvironmentSung Keun Park,

    Korea Detector Laboratory, Korea University, Seoul, Korea